Mixing systems and methods of mixing

ABSTRACT

A system for mixing and mixing processes and structures are disclosed. In addition a nozzle used for mixing is disclosed.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.12/577,529, filed Oct. 12, 2009, which is hereby incorporated byreference in its entirety.

FIELD OF THE INVENTION

The present invention relates to mixing systems, methods, and componentsused for mixing fluids, and particularly fluids at wastewater treatmentfacilities.

BACKGROUND

Methods and systems for treating wastewater are known in the art. Suchmethods may include aerobic, anoxic, and anaerobic processes.

SUMMARY OF THE INVENTION

The present invention includes a mixing system for mixing fluids. Themixing system may be used for mixing wastewater in a wastewatertreatment containment unit. The system includes a source of compressedair connected to a supply line; a valve between the source of compressedair and a supply header; a first line connected to the header; and anozzle located inside a containment unit, wherein the nozzle isconnected to the first line and wherein the nozzle comprises twooutlets.

The present invention further includes a nozzle for use in a mixingsystem with the nozzle having a nipple interconnected to a structureforming or capable of forming a partially enclosed channel, and thechannel having at least two outlets.

The present invention also includes a process for mixing includingintroducing an intermittent and controlled burst of pressurized gas froma nozzle into a containment unit. In the process, multiple mixingbubbles of varying sizes are formed by the burst, and at least twopluralities of mixing bubbles are introduced nearly simultaneously froma single nozzle.

The present invention may be better understood by reference to thedescription and figures that follow. It is to be understood that theinvention is not limited in its application to the specific details asset forth in the following description and figures. The invention iscapable of other embodiments and of being practiced or carried out invarious ways.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention are better understood when the following detailed descriptionis read with reference to the accompanying drawings, wherein:

FIG. 1 is an overhead perspective view of a mixing system in accordancewith an embodiment of the present invention;

FIG. 2 is a partial perspective view of the mixing system shown FIG. 1;

FIG. 3 is a front cut-away view of a controller box in accordance withan embodiment of the present invention;

FIG. 4 is a detailed view of a supply header of the present inventionhaving five nozzles, wherein each nozzle is connected to the supplyheader by way of a first line and a second line;

FIG. 5 is a close-up view of a nozzle from FIG. 4 that is connected tothe supply header by way of a first line and a second line;

FIG. 6A is a front, cut-away view of an embodiment of a nozzle of thepresent invention in which the spacers (shown if FIG. 6B) are omittedfor clarity.

FIG. 6B is an end view of the nozzle shown in FIG. 6A;

FIG. 6C is a top view of the nozzle depicted in FIG. 6A;

FIG. 7 is a drawing showing the flow of gas into and out of the nozzledepicted in FIG. 6A;

FIG. 8 is a side view of the nozzle shown in FIG. 5 showing risingmixing bubbles;

FIG. 9 is a drawing that provides a representation of pathways createdby the mixing system of the present invention;

FIG. 10 is a drawing depicting an embodiment of a mixing method of thepresent invention in an aerobic wastewater treatment process; and

FIG. 11 is a graph comparing mixing test results of the presentinvention with mixing test results of a conventional mechanical mixer.

Repeat use of reference characters in the present specification anddrawings is intended to represent same or analogous features or elementsof the invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Reference will now be made in detail to various embodiments of theinvention, one or more examples of which are illustrated in theaccompanying drawings. Each example is provided by way of explanation,not limitation, of the invention. In fact, it will be apparent to thoseskilled in the art that modifications and variations can be made in thepresent invention without departing from the scope and spirit thereof.For instance, features illustrated or described as part of oneembodiment may be used on another embodiment to yield a still furtherembodiment. Thus, it is intended that the present invention covers suchmodifications and variations as come within the scope of the appendedclaims and their equivalents.

Referring to FIG. 1, an overhead perspective view of an exemplarywastewater treatment mixing system 1 is shown. The system 1 includes acontainment unit for wastewater, which is shown in FIG. 1 as basin 2having four sidewalls 4 and a bottom 6. One of ordinary skill in the artwill appreciate that alternative types of containment units, such astanks or vessels, are also within the scope of the present invention.The containment unit may additionally have an inlet through whichwastewater enters and an outlet through which the treated wastewaterexits. In some embodiments, the containment unit may allow forcontinuous flow of the wastewater whereas other embodiments may restrictthe flow of the wastewater. In some embodiments, multiple containmentunits, of the same type or of differing types, may be present andconnected such that the wastewater passes to and through themsequentially as it is treated and/or processed. The remaining componentsof the wastewater treatment mixing system 1 of the present invention areshown in more detail in additional figures and described therewith.

FIG. 2 is a partial perspective view of the mixing system shown FIG. 1.As shown in FIG. 2, a source of compressed air is shown outside of basin2 as a compressor 8. Compressor 8 is connected to supply line 10, whichfeeds into a controller box 12. A conventional regulator 9 may be placedalong the supply line to regulate the pressure of pressurized gas fromthe compressor 8. In the depicted embodiment, controller box 12 islocated outside of basin 2, but it is understood that the preciseplacement of controller box 12 may vary.

Controller box 12 is shown in further detail in FIG. 3, in which, in theparticular embodiment depicted, controller box 12 includes eight valves14 with each having a solenoid valve 16. Valves 14 are connected withsupply line 10. Each valve 14 has an exhaust pressure sensor 15 that isin communication with a programmable logic controller 20. Each pressuresensor 15 provides a signal to the programmable logic controller 20 eachtime the valve 14 to which it is attached opens and closes. If thesignals do not fall within a predetermined range, the programmable logiccontroller 20 generates a fault signal to the plant process controlsystem (not shown) or to the operator. In this manner, mixing system 1includes an alert for certain malfunctions, such as when a valve 14 isstuck open or stuck closed. The programmable logic controller 20, whichcan include a memory (not shown) and a processor (not shown), is alsocapable of selectively opening and closing each valve 14 located incontroller box 12. Obviously, systems may also be utilized in thecontext of this invention that use manual manipulation of valves insteadof the computerized control system described above.

Referring again to FIG. 2, four supply headers 18 made of PVC piping areshown, wherein each supply header 18 is connected to a valve 14 incontroller box 12. Supply headers 18 extend from controller box 12toward bottom 6 of basin 2. Supply headers 18 also extend in a patternparallel with bottom in an arrangement in which they are atsubstantially equally-spaced intervals. As apparent to an ordinaryartisan, supply headers 18 can be made of a single, continuous componentor, in an alternative embodiment, supply headers 18 can be constructedfrom multiple components joined by conventional measures, such aswelding, adhesive, threading, bending, use of a connector, or otherknown measures or combinations thereof. In addition, the headers, aswell as all of the piping in this system, can be of any construction andmaterial that meets the particular needs of the mixing system. Forexample, the piping can be made from plastic, galvanized steel, or anyother material from which piping is typically formed and which meets therequirements of the particular system. It should also be appreciatedthat in other embodiments, the location of supply headers 18 can bevaried. By way of example, headers 18 can run above basin 2.

In the embodiment depicted in FIG. 2, and as also shown in more detailin FIG. 4, each of the supply headers 18 has five first lines 22 thatextend substantially perpendicular from each supply header 18 and thatare substantially parallel to bottom 6. It is understood that firstlines 22 can extend at different angles in other embodiments. As seen inFIG. 5, first lines 22 are connected to supply header 18 using a T-typeconnector 19 with cap 21 sealing the unconnected branch, although anyconventional means for connecting can be employed and such means arereadily known to a person having ordinary skill in the art.Alternatively, for example, supply header 18 can be integral to firstline 22. Although first lines 22 are depicted in a staggered layout,i.e., each first line 22 extends in the opposite direction from theprevious and subsequent first lines 22, other layouts are within thescope of the present invention. Although, certain advantages may beachieved with the particular layout depicted in the figures hereof.

Attached to each first line 22 is a second line 24, which extends in thesame general direction as sidewalls 4. As shown in FIGS. 2, 4, and 5,each second line 24 is connected to a nozzle 30 at the distal end ofsecond line 24 opposite the supply header 18. The connection betweensecond line 24 and nozzle 30 can be made by any conventional measures,such as those discussed above. It is understood that in otherembodiments, the second line 24 can extend at different angles. In thedepicted embodiment, as best shown by FIG. 5, first line 22 and secondline 24 are connected using a T-type connector 23 and are generally at a90° angle with respect to one another. In FIG. 5, nozzle 30 is shown inblack shading.

Although one of ordinary skill in the art will appreciate that varioustypes of nozzles can be used within the scope of the present invention,a particular embodiment of the present invention is shown in detail inFIGS. 6A, 6B, and 6C. With reference to these figures, nozzle 30 has anipple 32, an upper plate 34, a lower plate 36, and spacer 37. Spacer 37is omitted from FIG. 6A for clarity. Nipple 32, which is hollow topermit gas flow, is connected to second line 24 (as shown in FIG. 5) andopens into channel 38. Upper plate 34 and lower plate 36 are parallel toeach other and are spaced apart by spacer 37 such that channel 38 isformed between them, wherein channel 38 has outlets 40 at each distalend. In other embodiments, multiple channels are present, wherein eachchannel may have an outlet at each distal end. By way of example, oneembodiment of a nozzle of the present invention has a nipple thatconnects with three channels, wherein each channel has an outlet at eachdistal end.

In other embodiments, channel 38 can be formed by two plates beingdirectly attached without a spacer wherein the plates have integralgrooves that align to form a channel. In yet further embodiments, thenozzle may be interconnected to a tube or pipe, wherein the hollowinterior of the tube or pipe functions as channel 38. It is recognizedthat one of ordinary skill in the art will readily appreciate otherstructures suitable to provide for channel 38. In an additionalembodiment the channel is formed by a single plate having a groove,wherein the plate is located against the bottom of a containment unitsuch that the groove and bottom collectively form a channel. In oneparticular embodiment of the present invention, the inner diameter ofthe nipple 32 measures one inch and the length measures nine inches; theupper plate is twenty inches long by four inches wide by 0.25 inchesthick: the lower plate is twenty inches long by seven inches wide by0.25 inches thick; the spacers are twenty inches long by two inches wideby 0.125 inches thick; and channel 38 and outlets 40 have a height(between upper plate 34 and lower plate 36) of 0.25 inches and a widthof three inches. In another embodiment, the lower plate is alternativelyten inches wide. In yet another embodiment, the spacers are one inchwide.

In some embodiments, the dimensions of the channels and outlets on anozzle are designed as a function of the number of outlets on thenozzle. For instance, and by way of example, nozzles having more outletsmay have narrower channels and outlets than an otherwise identicalnozzle having fewer outlets. Similarly, it will be appreciated that thelength of a channel can influence the design dimensions of its channeland outlet. In addition, in some embodiments, outlets on a nozzle may bespaced such that adjacent outlets are no closer than the width of theoutlets.

In operation, wastewater treatment mixing system 1 functions to mix thecontents of basin 2. System 1 operates by compressor 8 providingpressurized gas into supply line 10. A conventional regulator may beutilized to control the pressure of the pressurized gas. The pressurizedgas is generally a gas or fluid that has a lower density than thewastewater mixture (including any added compounds) that is present inbasin 2. The pressurized flows through supply line 10 to the valves 14in controller box 12. Each valve 14 is capable of opening and closing toselectively and controllably allow the pressurized gas to flow into thesupply header 18 corresponding to that particular valve 14. When a valve14 is opened, the pressurized gas flows into the respective header 18for that valve. In one embodiment, the opening and closing of the valvecan be controlled by the programmable logic controller 20. In others,the opening and closing of the valve(s) can be controlled manually.

In one embodiment, no more than one valve 14 within control box 12 isopen at any given time. When a valve 14 is open, the pressurized gasflows into and through a header 18 corresponding with that particularvalve 14. As sufficient pressurized gas flows into header 18, it willalso fill first line 22 and second line 24. The gas flow continues intonozzle 30. The flow of gas in nozzle 30 of FIG. 6 is shown by arrows inFIG. 7. As shown, the gas flows into nozzle 30 by entering nipple 32 andthen continues to channel 38 and toward outlets 40. In generaloperation, valves 14 are opened in short, cyclic intervals.

As a result of the bursts of gas exiting nozzle 30 through outlets 40and entering basin 2, nozzle 30 generates a plurality of mixing bubbles50 in basin 2 that are generally larger in size than the bubblesintroduced to the system by conventional aerators used in an aerationprocess for treating wastewater. Some wastewater processes utilizediffusers that generate small bubbles and the diffusers are not operatedin a generally cyclical interval. In the present invention, nozzle 30 isused to introduce cyclic, controlled bursts of compressed gas or otherfluid to the contents of basin 2 as shown in FIG. 8. The bubbles createdby the present invention may be generally repeatable at distinctintervals as desired by the particular fluid mixing flow desired.

Mixing bubbles 50 may vary in size, and various parameters may influencethe size of the mixing bubbles, such as the size of channel 38 andoutlets 40, the flow rate of the pressurized gas, and the density of thepressurized gas. Generally, when similar supply headers, lines, andnozzles are used throughout a system, mixing bubbles of generally thesame volume and size will be formed by each nozzle in the system whenoperating under similar conditions. Mixing bubbles 50 are generallylarger than bubbles created by conventional aerators used in aerationprocesses for treating wastewater. However, in one embodiment of thepresent invention, none of mixing bubbles 50 exceed a diameter of sixinches. Because the pressurized gas forming mixing bubbles 50 is lessdense than the surrounding liquid composition in basin 2, mixing bubbles50 rise away from bottom 6 of basin 2 as shown by the arrows in FIG. 8.It should be noted that the mixing bubbles shown in FIG. 8 and allsubsequent figures are representative only and are not to scale. Themixing bubbles of the present invention may vary in quantity and sizefrom the depicted representations and their physical characteristics aredependent on a variety of factors as mentioned above.

As mixing bubbles 50 rise, a displacement of the adjacent fluid withinbasin 2 occurs. In particular, the rising mixing bubbles 50 exert aforce in an upward direction, and a vacuum is created behind thebubbles. This vacuum can be present behind individual bubbles and canalso be present from a grouping of mixing bubbles 50 resulting from agas burst. The vacuum pulls surrounding fluid from the area aroundbottom 6 of basin 2 toward the surface (in the direction of the risingmixing bubbles 50).

The cumulative effect of the periodic release of mixing bubbles 50 isthe generation of at least one circular pathway of liquid within thecontainment unit. As used herein, the term “circular pathway” indicatesthat near the surface of the liquid level there is a downwardly directedcirculation pathway of the fluid.

An example of a possible circular pathway created by the rising mixingbubbles 50 and the trailing vacuum created thereby is depicted by thearrows in FIG. 9. As shown in FIG. 9, mixing bubbles 50 have risen awayfrom bottom 6 of basin 2. As a result, a circular pathway shown by thenon-dashed arrows is created. In addition, the dashed arrows in FIG. 9show an additional pathway that can be created by the rising of thebubbles and the vacuums associated therewith. It is understood thatthese pathways are representative only, and a person of ordinary skillin the art can readily appreciate that additional, alternative, anddifferent pathways can be created by the present invention.

The periodic bursts of pressurized gas from nozzles 30 as describedabove can be controlled and varied in terms of both timing and volume toachieve a desired circulation pathway. In particular, particular valves14 can be selectively opened and closed to permit a desired amount ofpressurized gas to enter into a particular supply header 18. Bycontrolling the pressurized gas entering each supply header 18, theresulting burst is also controlled. In a like manner, a desired sequenceof bursts from nozzles 30 in communication with different supply headers18 can be achieved by controlling the sequence of pressurized gasentering supply headers 18. For instance, in one embodiment the sequenceof pressurized gas releases may be timed to move along the basin in thedirection of wastewater flow before the pattern is cyclically repeatedto create a wave-like effect.

In some embodiments of the present system, first lines 22 and secondlines 24 have an equal inner diameter that is smaller than the innerdiameter of supply header 18 to which they are in communication. Inother embodiments, first lines 22 have an inner diameter equal to theinner diameter of the supply header 18 to which it is connected, and thecorresponding second lines 24 has a smaller inner diameter. In such anembodiment, supply header 18 and first lines 22 fill with thepressurized gas before pressurized gas enters any adjoining second lines24. This flow pattern of pressurized gas results from the wider diametersupply header 18 and first line 22 offering a lesser path of resistanceto the pressurized gas than the smaller diameter of second line 24. Insuch an embodiment, after supply header 18 and first line 22 have filledwith pressurized gas, each second line 24 connected to that headerbegins to simultaneously fill with pressurized gas that then flows intothe connected nozzles 30 at the same rate. In this manner, thepressurized gas entering each nozzle 30 is controlled so that theresulting burst described above occurs simultaneously and of equalmagnitude for each nozzle 30 in communication with the same header 18.In even further embodiments, first line 22 has a smaller inner diameterthan supply header 18 to which it is connected, and the correspondingsecond line 24 has a smaller inner diameter than the second line 24. Itis appreciated that the use of vertical line between the supply headerand nozzle is useful to prevent fluids from the containment unitentering the lines or supply header.

In yet another embodiment, the system may not include a first line 22,and second line 24 may connect to supply header 18. In such anembodiment, second line 24 may also have a smaller inner dinner thansupply header 18 to permit equal flow of the pressurized gas in eachsecond line 24 and to each nozzle 30 as described above. As indicated,second line 24 may be a vertical pipe or line extending from first line22. However, if improvements can be made to achieve the results of thepresent invention without the use of a vertical pipe, those are withinthe scope of this invention.

The system of the current invention includes nozzles in a variety ofpatterns within a containment unit. As shown in the exemplary embodimentshown in FIGS. 1-2, nozzles 30 are displaced throughout basin 2 in agrid pattern, with five nozzles in communication with each supply headerby way of a second line 24 and a first line 22, and the nozzles areshown in a staggered pattern. In other embodiments, more or fewernozzles can be in communication with a header. In yet other embodiments,the arrangement of the nozzles can vary, including being on the sameside of a supply header (as opposed to staggered). In addition, in evenfurther embodiments, the supply header may be of a circular shape orserpentine shape as opposed to the linear grid depicted in FIG. 1. Theparticular arrangement of a mixing system of the present invention candepend upon the size of a containment unit and the particular processbeing performed, and additional and alternative arrangements areappreciated by a person having ordinary skill in the art. In someembodiments, the nozzles may be placed approximately five to ten feetlongitudinally along a supply header and offset approximately one tofour feet from the header.

As shown in the embodiment in FIGS. 1-2 and 3-5, nozzles 30 are locatedon the bottom of the basin. In some embodiments, nozzles 30 can beattached to the bottom 6 of basin 2. In yet other embodiments, nozzles30 are placed above the bottom 6 of basin 2.

The present invention has numerous applications. For instance, in awastewater treatment system, the present invention can increase contactbetween the wastewater, chemical additives, gas additives, and theworking bacteria in the containment unit. By way of example, and withoutintending to limit the scope of the invention, the present invention canbe used in an aerobic process for treating wastewater. In such anaerobic process, conventional aerators or diffusers are placed on ornear the bottom of a containment unit. The aerators introduce diffusedoxygen into the containment unit, thereby generating small bubbles. Anaerobic process also generally includes bacteria and othermicroorganisms in the wastewater. The oxygen, bacteria, and othermicroorganisms convert ammonium in the wastewater to nitrate vianitrite, and an anoxic process can then be used to convert the nitrateto an environmentally-harmless nitrogen gas.

To improve the conversion of the ammonium, mixing within the containmentunit of the components may be desired. Whereas aeration bubbles maycause some limited mixing, the influence of the aeration bubbles on thesurrounding fluid is limited and only produces a significant effect inthe area immediately surrounding the diffuser. Using the system andprocess described above, improved mixing can be achieved in the aerobicprocess. In particular, the present invention can provide turbulentdisplacement of the liquid, gases, bacteria, and microorganisms in thecontainment unit and thereby beneficially increase the contact of thecomponents. In addition, increased retention time of other gases in thesystem may be achieved.

This above-described application of the present invention in an aerobicwastewater treatment process is illustrated further by FIG. 10, in whichonly a portion of a nozzle and segment of the containment unit arerepresented. The “x” designations in FIG. 10 are representative ofbacteria and microorganisms present in the fluid within the containmentunit. Aerator 60, which is more typical of a wastewater unit diffuser,generates diffused oxygen bubbles 62. Mixing bubbles 50 in FIG. 10 areshown as having already risen away from the bottom 6 of basin 2, and theresulting pathways shown by the arrows are generated as described above.The bacteria and microorganisms can be turbulently mixed (as representedby wobbling arrows) by the pathways created by the system of the presentinvention as described above, thereby increasing the contact between thecomponents in the containment unit. A person having ordinary skill inthe art will appreciate the representative nature of FIG. 10 as anexample only and recognize that additional mixing can occur thanrepresented by the arrows.

In a similar manner, the present invention can be used to improve mixingin an anoxic wastewater treatment process. As described above, thepresent invention can be used to increase contact between thewastewater, bacteria, and microorganisms in such a process. Inparticular, because anoxic processes operate in the absence of dissolvedoxygen, the minimal mixing provided by aerators in an aerobic process isnot present and the present invention is advantageous.

As indicated above, a person having ordinary skill in the art willappreciate that the present invention may also be used in otherprocesses and systems. For instance, and without limitation, the presentinvention may be used in sludge digesters, anaerobic wastewatertreatment containment units, wastewater channels, sludge holding tanks,equalization tanks, and pump stations in the same manner described abovewith any deviations being readily known by a person having skill in theart.

In addition, the present invention can be used in conjunction with otherconventional structures or components. For instance, the system andnozzle of the present invention can be used in conjunction with one ormore mechanical mixers. In addition, the present invention can be usedin conjunction with an Integrated Fixed-film Activating Sludge (“IFAS”)system that includes media. Such media are suspended in the wastewaterand provide bacteria and other microorganisms a structure on which toattach. Likewise, a knitted matrix fixed-film media, such as thecommercially available BioWeb™ product sold by Entex Technologies, canbe used in conjunction with the present invention to provide points ofattachment for biomass growth. An anchored net, web, or similarstructure that may provide another structure upon which the bacteria andother microorganisms can attach can be used in conjunction with thepresent invention. In some embodiments, any combination of theseadditional components can be employed, such as both an IFAS and a net,web, or similar structure.

The present invention is understood to achieve mixing that is equivalentto or better than that which is achieved using known mechanical mixers.For instance, a test was conducted in which the efficiency of a nozzleof the present invention was used and compared with a mechanical mixercommercially sold under the brand name Flygt S4660. In the test,Rhodamine WT, a known chemical tracer with the ability to absorb greenlight and emit red light, was added to a composition that was mixed in abasin. The basin in which the test was conducted had dimensions of 55ft×41.5 ft×24 ft, resulting in a total volume of 409,754 ft³.

In one trial, the present invention was tested in an embodiment havingfour headers, wherein each header was in communication with a fournozzles by way of a first line and a second line. As described above, aseparate valve was in communication with each header to selectivelypermit compressed gas to enter each header. Compressed air at 30 psi wasselectively and consecutively fed into each header for 0.5 seconds, witha total of 5.5 seconds elapsing between the pressurized gas enteringeach header. Thus, each valve was opened for 0.5 seconds every 24seconds to permit the compressed air to flow into the headercorresponding to that valve. In a separate trial, a single commerciallyavailable 15 horsepower mechanical mixer sold under the brand name Flygtwas used in the same basin.

A meter was used to measure the concentration of Rhodamine WT at a pointnear the exit of the basin, and samples were taken at a central point inthe basin and the Rhodamine WT was measured. As shown in FIG. 11, inwhich the concentration of the Rhodamine WT is compared over the time ofmixing for both the present invention and the tested mechanical mixer,the present invention generally mixed as well as the mechanical mixer.The present invention is indicated in the legend of FIG. 11 as “BioMix,”and the mechanical mixer is indicated at “Flygt.” In particular, thegraph shows that the concentration of the Rhodamine WT is comparablymixed by the present invention as compared with the tested mechanicalmixer.

In addition, the test described above further indicates that the nozzleof the present invention mixed in a more energy-efficient manner. Inparticular, the following parameters applied respectively to each trial:

Present Invention Mechanical Mixer Power Factor 0.91 0.55 Amps 6.8022.00 Volts 483.07 467.65Using the parameters above, the horsepower and kilowatts required toobtain the results shown in FIG. 11 can be calculated using thefollowing equations, in which “p.f.” represents the power factor:

${HP} = \frac{{Amps}*{volts}*\sqrt{3}*{p.f.}}{746}$${kW} = \frac{{Amps}*{volts}*\sqrt{3}*{p.f.}}{1000}$

Using this equation, the present invention required only 6.91 horsepowerand 5.155 kW, whereas the mechanical mixer required 13.14 horsepower and9.801 kW to achieve comparable mixing results. These results indicatethat the nozzle of the present invention operated 190% more efficientlythan the conventional mixer. Assuming an electricity cost of $0.06 perkilowatt hour and 8760 hours per year of operating the compressor, thepresent invention represents a savings of $2442.08 per year to achievecomparable in mixing in the containment unit tested. In addition, thepresent invention does not require mechanical or electrical componentsto be present within the containment unit, but instead utilizescompressed air.

The foregoing description of illustrative embodiments of the inventionhas been presented only for the purpose of illustration and descriptionand is not intended to be exhaustive or to limit the invention to theprecise forms disclosed. Numerous modifications and adaptations thereofwill be apparent to those of ordinary skill in the art without departingfrom the scope of the present invention.

It will be understood that each of the elements described above, or twoor more together, may also find utility in applications differing fromthe types described. While the invention has been illustrated anddescribed in the general context of mixing in wastewater treatmentsystems and processes, it is not intended to be limited to the detailsshown since various modifications and substitutions can be made withoutdeparting in any way from the spirit and scope of the present invention.As such, further modifications and equivalents of the invention hereindisclosed may occur to persons skilled in the art using no more thanroutine experimentation, and all such modifications and equivalents arebelieved to be within the spirit and scope of the invention as describedherein.

1. A process for mixing in a wastewater treatment system comprisingsimultaneously introducing at least two intermittent bursts ofpressurized gas from a nozzle and into a containment unit in awastewater treatment system.
 2. The process of claim 1 wherein the atleast two intermittent bursts of pressurized gas are introduced into thecontainment unit simultaneously from opposing distal ends of a fluidpassage of the nozzle.
 3. The process of claim 2 wherein the at leasttwo intermittent bursts of pressurized gas are introduced at or near thebottom of the containment unit.
 4. The process of claim 1 wherein thecontainment unit comprises wastewater disposed therein.
 5. The processof claim 1 wherein the process comprises simultaneously introducing atleast two intermittent bursts of pressurized gas from a second nozzle.6. The process of claim 5 wherein the at least two intermittent burstsof pressurized gas from the nozzle and the at least two intermittentbursts of pressurized gas from the second nozzle are introducedsubstantially simultaneously.
 7. The process of claim 5 wherein the atleast two intermittent bursts of pressurized gas from the nozzle and theat least two intermittent bursts of pressurized gas from the secondnozzle are introduced intermittently.
 8. The process of claim 1 furthercomprising supplying pressurized gas to the nozzle through a header anda first line.
 9. The process of claim 8 further comprising supplyingpressurized gas to a second nozzle through a second header andintroducing at least two intermittent bursts of pressurized gas to thecontainment unit from the second nozzle.
 10. The process of claim 9wherein the nozzle introduces at least two intermittent bursts ofpressurized gas to the containment unit at a distinct interval from theintermittent bursts of pressurized gas from the second nozzle.
 11. Theprocess of claim 10 wherein the intermittent bursts of pressurized gasfrom the second nozzle is introduced cyclically with respect to theintermittent bursts of pressurized gas from the nozzle.
 12. The processof claim 4 further comprising treating wastewater in the containmentunit with an aerobic, anoxic, or anaerobic process.
 13. The process ofclaim 8 further comprising supplying pressurized gas to the nozzlethrough a second line that is generally perpendicular to the first line,wherein the second line is located between the first line and thenozzle.